The Court of Appeal has dismissed three cases in which it was claimed police have been misusing number plate identification technology for crime fighting.

Police officers are accessing the privately-owned automated systems more and more to see whose vehicle is where and when, with use climbing to 700,000 times last year, up 20%.

Lawyers for three defendants argued this was too loose, that police should need a warrant or similar in order to use the evidence in court.

But the court disagreed, ruling the evidence obtained from Auror - one of the two private companies with automated number plate recognition (ANPR) systems that police use - was admissible.

It is expected that might be appealed to the Supreme Court.

The ruling follows a two-day hearing a year ago that followed district court proceedings.

The three appeal court judges imposed strict limits on media reporting as the cases are still live.

The charges against the appellants were disqualified driving, property damage, and burglary.

Auror markets its technology here and in Australia, the UK and US as a retail crime fighting tool. It has partnered with NZ police for over a decade, with usage jumping since 2020, leading to a spike in shoplifting, assault on staff and other retail crimes being accepted by officers for investigation.

The ruling described how Auror can provide a list of detections for a vehicle for up to a 60-day period and links to CCTV footage which police could download. This was more comprehensive and efficient than old ways of investigating, it said.

Rising use

Separately from the court proceedings, police have updated their figures about using the technology.

A police tech report said usage of Auror had "plateaued" at about a quarter of a million requests a year for number plate information on about 80,000 vehicles by about 3000 officers.

But police use of a second system continues to rise rapidly. Their requests to another Auckland company, SaferCities, were up by a third to 450,000 requests last year linked to almost 100,000 vehicles.

This was likely because of "further expansion of this network across the country and broader awareness within police of the utility of SaferCities information ... similar levels of growth were seen in the Auror platform during the first few years of its availability to registered Police users", said the report.

The systems are not used much for live tracking a vehicle - just a couple of hundred times a year each.